Secret-service system for interconnecting telephone-lines.



PATENTED SEPT. 26, 1905. A. K ANDRIANO & H. HERBSTRITT. SECRET SERVICE SYSTEM FOR INTERCONNEOTING TELEPHONE LINES.

APPLICATION FILED JAN. 26, 1901.

2 SHEETS-SHEBT 1.

PATENTED SEPT, 26, 1905. HERBSTRITT.

A. K. ANDRIANO & H.

SECRET SERVICE SYSTEM FOR INTERGONNEOTING TELEPHONE LINES.

APPLICATION FILED JAN. 26, 1901.

2 SHEBTSSHEET 24 UNITED STATES I PATENT OFFTCE.

ALBERT K. ANDRIANO AND HERMANN HERBSTRITT, OF SAN FRANCISCO, CALIFORNIA, ASSIGNORS, BY MESNE ASSIGNMENTS, TO DIRECT-LINE GENERAL TELEPHONE COMPANY, OF SAN FRANCISCO, CALIFORNIA,

A CORPORATION.

Specification of Letters Patent.

Patented Sept. 26, 1905.

Application filed January 26, 1901. Serial No. 44,838.

To (Ll/Z whom it may concern:

Be it known that we, ALBERT K. ANDRIANO, a citizen of the United States, and HERMANN Hnnnsrnrrr, a subject of the German Emperor, residents of the city and county of San Francisco and State of California, have invented new and useful Improvements in Secret-Service Systems for Interconnecting Telephone-Lines, of which the following is a specification.

This invention relates to improvements made in telephone systems that provide a directconnection and a signaling or calling-up means between one station and another without employing a central station and an operator.

The improvements have for their object to prevent a third party from switching onto the line and listening to the conversation between two connected stations; to provide a circuit between two stations from which all the remaining stations are for the time being cut off without interfering with the operations of calling up and talking with any station not in use; also to provide ameans of notifying a party when switching to the line of another station that the line is already in use and at the same time rendering his receiver inoperative.

0 The improvements herein consist in novel means of controlling the talking-circuit of a station from or through the signaling-circuit, or ringing-circuit, as it is commonly called, in such manner that the completion of a closed circuit for talking between two stations is made dependent upon the ringing-circuit being completed and the bell at the called station being rung from the calling-station.

The improvements include also a novel 40 means of cutting out or rendering the receiving instrument of a station inoperative by throwing on its circuit a sound-producing device whenever the line with which it may be connected through the switching device of the station is already in use.

The improvements include certain novel construction and combination of switching devices, circuit-controllers, and sound-producing devices, as hereinafter fully described,

5 and pointed out in the claims at the end of this specification, in which reference is had also to the accompanying drawings, forming part thereof.

Figure 1 of the drawings is a front view of a telephone outfit and a switching device for a station in an eight-party system, the front of the case being removed. The switch is here represented standing on the home contact and the receiver on the hook. Fig. 2 is a front view of the same mechanism,showing the position of the parts when the receiver is taken down for use and the switch moved away from the home contact. Fig. 3 is a detail, on an enlarged scale, of parts of the mechanism that are controlled by the mov- 5 able arm of the switching device. Fig. 4c is a diagram showing the circuits for three stations and the common ringing-circuit. Fig. 5 is a detail of the insulated stop on the frame of the sound-producing magnet.

In this improvement the receiving and transmitting instruments at each station are disconnected from the line when the station is not in use and properly connected in circuit with another station for talking, first, by opcrating the switching device at the callingstation, and, secondly, by pressing the ringing-key to call up the party at the opposite station on the line after the switch has been set. By these two operations the circuit in 0 which are included the telephone instruments at the calling-station is completed and rendered operative; otherwise it is opened at that point and cannot be used. The ringing-circuit completed at that time between the two 5 stations'is so controlled by the conditions at the called station that if the circuit at that station is closed and the instruments are in use the receiving instrument at the callingstation will be disconnected, so as to be inop- 9o erative; but if the receiving-station be out of use at the time of switching the party at the calling-station will connect his own instruments in circuit and put them in operative condition when he presses his ringing-key. On the other hand, if the receiving-station be busy the receiver at the calling-station will give a buzzing sound if he removes it from the hook and puts it to his ear, and the noise set up in the receiver notifies the party listening that the line is busy. If he keeps the re- IOO ceiver off the hook and attempts to listen to the conversation, the noise thrown in the receiver by the sound-producing device prevents the conversationfrom being understood by the party at the third station.

In carrying out this invention the line containing the transmitter and the receiver of a station is broken or opened at a point between the battery to and the line-terminal belonging to the station or between that terminal and the return-wire of the line-circuit, and at that break or opening two circuit-closing springs 2 3 are situated in close relation to one end of a movable lever 5, which in one position holds the contacts 2 3 apart, but in another position allows one spring to touch the other and close the break at that point. This opening is in addition to the usual break that is made at the contact-springs (a f in the circuit between the battery and the transmitter and receiver and which are controlled by the rising and falling movements of the telephone-hook for the purpose of preventing waste of battery force when the telephone is not in use. The lower end of the lever 5, engaging a pin 7 on the detent g of the switch, is moved to one side when the hooked end of the detent rides on the ratchet-toothed hub it of the movable arm is of the switch. As often as the switch-arm is shifted from one stationary contact 20 to another the upper end of the lever moves in the opposite direction, touching the contact-spring 2 and pressing one spring away from the other. A coiled spring 6, attached to the lever 5, draws its upper end away from the contact 2 and allows the two springs 2 3 to make metallic contact when the point of the detent rests in the teeth of the hub. These movements of the lever 5 are controlled by a locking-lever 8, loosely supported on a pivot in a bracket 9 and having on one end a pin 10, engaging the lever 5, while the other end, lying in close relation to the poles of an electromagnet 14, forms the armature of that magnet. On passing a current through it the magnet attracts the lever 8, setting its outer end away from the wide portion of the lever 8 and in a shoulder 12 at the junction of the wide and narrow portions of the lever, thereby allowing the lever to move sufiiciently to one side under the tractile force of the spring 6 to let the contact-spring 2 touch the adjacent con tact 3 and close the break at that point. The parts remain in such position as long as the end of the locking-lever 8 rests against the shoulder 12; but immediately on moving ofi the shoulder and against the wide portion of the lever 5 the locking-lever holds the end of the lever 5 against the contact 2 and opens the circuit at that point. The lever 5 stands in that position when the station is not busy; but as soon as the magnet 1 1 is energized it attracts the locking-lever 8 and releases the circuit-breaking lever 5, thereby allowing the coiled spring 6 to draw the end of the lever 5 away from the contact 2 sutliciently to let the two contacts 2 3 touch each other.

The magnet 14 is connected with one side of the ringing-battery m by a wire 32, running from the magnet to the line-wire c, which connection is constant; but connection is made with the other side of the battery and is controlled in one way through the direct-line wire and the switching device of the station mechanism and in another way through a circuit in which is included a circuit-breaking device, the construction and operation of which will be hereinafter explained. These connections are made by the wire 32 from the coils of the magnet to the ringing-battery wire 4) and by a wire 36 running from the magnet-coil to one of a pair of contacts 29 30, the other contact of the pair being connected by a wire 35 to the back-stop 41 of the ringing-keyp. In close relation to these two contacts a third contact 31 is connected with the frame or bracket of the magnet. The three stops 29 3O 31 are situated in such close relation to the arm of the telephone-hook (Z that the arm on rising will bring the movable contact 29 against the stop' 31. When the two stops 29 30 are allowed to touch each other, the line wire between the two stations already connected through their respective switches is brought in and made a part of the ringing-circuit as soon as the party at the calling-station presses his ringing-key, for the reason that the movable stop 38 of the ringing-key is connected by wires 37 27 28 with the movable arm of the switch, and the circuit is completed as soon as the stops 38 and 41 come into contact. If the receiver at the calling-station is on its hook, a current will pass through the magnet 14. when the ringing-key is pressed, and the magnet will be energized at the same time that the bell at the opposite station is rung. The circuit at such time is traced from one side of the ringing-battery in through the wire 2; and the wire 32 at the calling-station to the magnet 14, and thence through the stops 29 30 and over the wire to the backstop 110f the ringing-key, the steps 29 30 being at that moment in contact with each other. At the ringing-key of the calling-station the circuit is completed through the two steps 38 41 and the wires 27 and 28 to the switch-arm Z7, and thence over the line-wire w, running to the other station, where the movable arm of the switch being at rest on its home contact the circuit is completed through the switch of the called station and the wires 28, 27, and 37 to the contacts 38 39 of its ringing-key and thence by the wires 24: 25 to the bell y, where the circuit is completed to the opposite side of the ringing-circuit by the wire 12. The

same movement of the ringing-key that rings up the opposite station also operates through the magnet the parts actuated by it and the spring 6 to throw the lever 5 from the contact 2 and close the break in the local circuit of the calling-station at the point 2 3. On the other hand, if the receiver at the calledup station be off its hook (Z the circuit previously traced will be open at the circuit-closing springs 33 34, they being held closed by the arm of the hook when it is down and opened whenever the hook rises, and consequently the magnet 14 will get no battery and will not act on the lever 5 when the ringingkey is pressed. Under this condition should the party at the calling-station remove his receiver from his hook he thereby short-circuits his magnet to the ringing-circuit and causes its armature to act as a sound-producing device. \Ve will now refer to those parts of the apparatus by means of which under the conditions now assumed a sound is produced that will interfere with the use of the receiver. The lifting of the hook (Z shifts the movable stop 29 from the stop 30 to that designated 31, thereby connecting the wire 36 from one side of the magnet 14 with the frame to which the lever 8 is pivotally attached, and thus bringing in this lever as a conducting part of the circuit. Situated directly over the end of the lever 8 is the stationary stop 15, insulated from the frame 9, as shown in detail in Fig. 5, and connected by a wire 16 with the side a of the ringing-circuit. It should be remembered that the normal positions of the parts at the local station (indicated in Fig. 1 and at the left-hand station in Fig. 4) are, with the lever 8, held by the spring 6 with its pin 10 against the shoulder 12 of the lever 5, so that the 10- cal circuit is not broken at 2 3, but that whenever the switch-arm 7c is moved away from its home contact the lever 5 is rocked by the pin 7 of the detent g and the lever 8 is moved i nto contact with the stop 15, thus putting the parts in condition for shortcircuiting the magnet and bringing the noise-producing devices into operation, these positions being represented in Fig. 2 and the middle station of Fig. 4. Under these conditions should a person attempt to get onto the line of another station already in use, whether he be legitimately trying to call up that station or attempting to overhear conversation passing over the line, (which is the condition indicated at the middle station of Fig. 4,) he will find that he cannot close the break 2 3 on his local circuit, while, on the other hand, the lever 8 at his magnet 14 is set in rapid motion, vibrating between the poles of the magnet 14 and the insulated stop 15, because the current passing from one side of the battery over the wires o 32 and through the coils of the magnet is short-circuited, being carried by the wire 36 and the stops 29 31 to the frame 9, and thence through the lever 8 to the insulated stop 15 and wires 16 and 42 to the opposite side a of the battery; but the lever 8 at such time being attracted by the magnet 14 is drawn away from the stop 15, and the circuit through the magnet 14 being broken it no longer holds down the lever 8, but the coiled spring 6, acting in the contrary direction to the magnet, immediately returns the lever 8 against the stop 15 and closes the circuit once more. It will be understood that the movements of the armature-lever 8 under these conditions are exceedingly short, so that the lever will not be drawn by the magnet far enough away from the stop 15 to allow its end to pass to the thin portion of the lever 5, and thus permit it to move so as to allow the break at 2 3 to be closed. By opening and closing the circuit through the magnet in this manner vibrating movements of the lever 8 on its pivot are produced, in making which it strikes rapid blows against the stop 15, and by connecting that stop in the circuit of the receiver 1) bya wire 17 the noise made by the lever is thrown into the receiver-circuit. The effect of this is to set up a buzzing sound in the ear of the listener when the receiver is used at such time, and the noise will continue until the receiver is hung up.

Contact-springs 18 19, located in the connection between the receiver 6 and the stop 15, are controlled by the lever 5 in such manner that when the end of that lever presses against the stop 2 and holds the local circuit open at 2 3 the movable spring 18 is pressed against the stationary spring 19 and the connection is closed; but as soon as the lever 5 is released by the lever 8 the springs 18 19 separate and cut out the sound-producing device from the secondary circuit at the same moment that the break in the local circuit is closed at the contacts 2 3.

If the connection between the receiver and the stop 15 and armature-lever 8 were merely mechanical, the noise produced by the striking of the latter against the former would probably be conducted to the instrument sufficiently to interfere with its use. We prefer, however, that the receiver should be in a circuit electrically connected with the circuit being interrupted in the manner described, so that there will be a certain flow of current through the receiver as the main circuit is opened and broken, thereby rendering the instrument inoperative for sound-receiving purposes.

The circuit through the receiver may be traced as follows: commencing at the wire 32, thence through the windings of the electromagnet by the wire 36 and the contacts 29 31 to the frame. The lever 5 being pivoted to the frame it then becomes a part of the circuit, beyond which it includes the contact 2, the wires leading to and from the receiver, thence by the contacts 18 19 and the wire 17 to the stop 15. Thence the circuit is completed over the line 16 to the ringing-circuit. It will be evident that the resistance of the circuit including the receiver is much greater than the circuit directly through the frame of the electromagnet, so that when the lever 8 is in engagement with the contact 15 but lit tle, if any, current passes through the receiver; but the moment the contact is broken at 8 15 the current is diverted through the receiver. This of itself will produce a cracking or rattling sound in the receiver, so that if the interrupting device comprising the armaturelever of the electromagnet made no sound still the receiver would be rendered inoperative.

As soon as the switch has been properly set and the ringing-key at the calling-station has been pressed the receiver and transmitter will be in operative condition when the receiver is removed from the hook, which is not done at the calling-station until after the switch has been set and the ringing-key pressed nor at the receiving-station until after the bell-signal has been received.

The movable arms of the switches at all the stations are kept on the home contacts at all times when the stations are not in use, and in that position they control the circuit-breaking levers 5, through the medium of push-rods 20, so as to keep the levers 5 away from the contacts 2 while the switches remain at rest on the home contacts. The upper end of the rod 20 is in line with and directly under the end of the lever 8, and its lower end rests on a pin 22 on the front face of the toothed hub 7b of the switch-arm, against which it is held by a coiled spring 21 on the rod. In the normal position of the switch-arm when at rest the pin 22 holds the rod against the lever 8 and keeps that lever in the same position it will take when it is drawn down by the magnet, and as long as the switch remains undisturbed the lever 8 will stand away from the contact 15 and the lever 5 be held away from the contact 2. The receiver may then be removed from its hook for use, and the break in the local circuit will remain closed; but when the switch-arm is moved to get on the line of another station the pin 22 is withdrawn from beneath the rod 20, and the coiled spring 21 thereupon draws the upper end of the rod away from the lever 8. The effect of this is to leave the lever free to move, and then as the pin on the detent g in the rising movement of that piece presses against the lower end of the lever 5 it sets the upper end against the spring 2, and the end of the locking-lever 8 immediately drops from the shoulder 12 onto the thicker portion of the lever 5. From this position, holding the contacts 2 3 apart, the lever 5 can be withdrawn only by bringing the magnet 14 in circuit with the ringing-battery over the line, as before described.

The particular form and arrangement of switching mechanism and circuits herein shown provide a full metallic circuit between the two stations composed of the direct line 10, terminating at the contacts to, and the return-wires 20, having contacts Q03 at the switch.

The switch-arm carries an additional contact-arm 7?, moving over a circuit-closing plate 414, from which a wire 15 runs to the secondary of the induction-coil. This part of the apparatus provided at each station is similar to switching devices already in use and is not claimed as a feature in the present invention. The switch-arm is automatically returned to position on the home contact by a spring whenever the telephone receiver is hung up; but as this feature is well known in the art we have not deemed it necessary to illustrate it.

The talking-circuit between two connected stations is readily traced in the diagram Fig. 4, where the switch in the first station on the left is set to the stationary contact belonging to the line of the third station. The parts at the latter station are in their normal positions of rest, while at station No. 2 a party is supposed to be trying to overhear the conversation between Nos. 1 and 3, having switched onto the line-contact of station No. 3, and thereby setting into operation the currentinterrupting device, that renders hearing through the receiver impossible. The arrangement of the talking-circuits at the several local stations does not form part of the present invention, and therefore may be changed from that shown. We have illustrated a local battery-circuit. The currents may be traced as follows: The local primary circuit, starting from the battery 0, goes by wire 16 to the primary windings of the induction-coil, thence to the transmitter, and from there to the contact f along the telephone-hook d and. the wires 27 and 37 back to the battery. The secondary or induced current, starting from the secondary coil, may be traced by the wire leading to the receiver through that instrument to the contacts 2 3, which now close the break at this point, thence by wire 48 to the contact 6, against which the telephone-hook cl bears. The circuit follows this hook, the wire 28 connecting it with the switch-arm 7r, that is bearing upon the point to of the line 10, leading to station No. 3. At that station the circuit is traced in a similar manner by switch-arm 71:, wire 28, hook (Z, wire 48, receiver 7), and wire to the secondary coil, thence by wire 15 to the contact-plate 14:, which is connected by the arm 70' of the switch with the return-wire Q02 of that station, by which latter wire the circuit is completed to the first station, where through the contacts 20 and 4:4, switch-arm k, and wire 45 the secondary coil is again reached.

l/Vhat we claim is 1. In a telephone system, a plurality of stations, switching devices operating to connect one station with another selected station, a common ringing-circuit including a ringingkey at each station, connected with one side of the ringing-battery and connectible with the other side of the battery through the circuit completed between two stations through the selecting devices and line-wires, an electrically-actuated sound-producing device at each station, means controlled by the switching device operating to bring the sound-producing device in the circuit of the receiving instrument and in the circuit of the ringingbattery by the act of moving the station-switch from its own line, and means operated through the movement of the ringing-key to throw the sound-producing device out of action when calling the distant station.

2. In a telephone system, the combination with a plurality of stations, having individual switching devices; of a ringing-circuitincluding a signal, a ringing-battery and a ringingkey, a sound-producing device at each station connectible in the receiver-circuit of the instrument, and comprising an electromagnet connected with one side of the ringing-battery, and connectible with the other side of the same battery through the ringing-circuit which is completed between a calling-station and the station being called, a short circuit in said magnet-circuit including a contact-stop connected with one side of the ringing-battery and a vibrating lever located between said stop and the poles of the magnet, a circuit-closing device controlled by the arm of the telephonehook and adapted to close the battery on the magnet directly through the ringing-circuit when the receiver of the station is on its hook, but to connect the magnet in circuit with the battery through the short circuit when the receiver is removed from the hook.

3. In a telephone system, stations having local transmitter and receiver circuits, a signaling-circuit including a common battery and circuitclosing devices at every station, a sound-producing device connectible in the receiver-circuit of the station, a switching device operating to connect the station with any selected station in the system, means controlled by said switch for connecting in the soundproducing device when the switch is moved away from the line of the station, and means actuated electrically from the signaling-circuit and operating to disconnect the soundproducing device at the signaling-station when the signal at the distant'station is operated.

4:. The combination with the transmitter and receiver circuits of a telephone-station; of a switching device, a circuit-closing device in the receiver-circuit, a lever controlling said circuit-closing device, a locking-lever operating to hold the circuit-closing lever in active position, a spring controlling said locking-lever, a battery, an electromagnet in circuit with one side of the battery, and connectible in circuit with the other side of the battery through a circuit-closing key, a circuit making and breaking device controlled by said magnet, means controlled from the movements of the telephone-hookfor connecting the magnet with one side of the battery through the circuit making and breaking device when the hook is allowed to rise, means connecting said circuit making and breaking device in the receiver-circuit and a circuitcloser in said connection controlled by the lever that controls the receiver-circuit, and operating in opposition to the circuit-closer in the receiver-circuit to close the circuit making and breaking device on the receiver-circuit when said circuit is opened.

5. In a telephone system, transmitting and receiving instruments, a battery and induction-coil, an electrically-'actuated sound-producing device, means actuated from the telephone-hook operating to connect said soundproducing device in the circuit of the receiver when the receiver is removed from the hook, and means controlling the sound-producing device and operating electrically to render the same inoperative by the current transmitted over the ringing-circuit between two stations connected for ringing up one station from the other.

6. In a telephone system, a plurality of stations, a ringing-circuit for the stations including a bell and ringing-key at each station, and means, operated upon the removal of the receiver, for short-circuiting the ringing-circuit when the station with which connection is sought to be made is busy, substantially as set forth.

7. In a telephone system, a plurality of stations, a ringing-circuit'for the stations including a bell and ringing-key at each station, a current-interrupting device in the ringingcircuit at each station, and means, controlled by the telephone-hook, operating to bring the said current-interrupting device in circuit if the station sought to be called be busy, substantially as set forth.

8. In a telephone system, a plurality of stations, a ringing-circuit for the stations, means operating upon the removal of the receiver, for short-circuiting the ringing-circut if the station sought to be called is busy, and a current making and breaking device in the said short circuit, substantially as set forth.

9. In a telephone system, a plurality of stations, a ringing-circuit for the stations, means operating upon the removal of the receiver, for short-circuiting the ringing-circuit if the station sought to be called is busy, and a current making and breaking device in the said short circuit, the said circuit making and breaking device being connected with the receiving instrument and arranged to render it inoperative for use in the hearing of conversation over the line, substantially as set forth.

10. In a telephone system, a plurality of stations, a calling-circuit for the stations, means, operated upon the removal of the receiver, for connecting such instrument with the calling-circuit if the station sought to be called be busy, and a current making and breaking device in the said circuit arranged to produce a disturbance in the receiving instrument so as to render the hearing of conversation passing over the line impossible, substantially as set forth.

11. In atelephone system, a plurality of stations, a calling-circuitfor the stations, means, operated upon the removal of the receiver, for short-circuiting the calling-circuit if the station sought to be called be busy, means for connecting the receiving instrument into said short circuit, anda circuit making and breaking device arranged to direct an interrupted current through the receiving instrument, substantially as set forth.

12. In a telephone system containing stations interconnected through local switching devices and line-Wires, the combination of means for interrupting or breaking the local circuit at a station, such means being operated by the local switching device When it is moved off its home contact, a ringing-circuit including a make-and-break device at each station by which a circuit is completed through. the bell at the called station, means electrically operated by the calling-circuit when the signal at the called station has been given, arranged to cause the closing of the local circuit with the line, and means operated upon the removal of the receiver from its hook for short-circuiting the calling-circuit and cutting out all distant stations if the receiver be removed Without first calling a distant station, substantially as set forth.

In testimony that We claim the foregoing We have hereunto set our hands and seals.

ALBERT K. immune. [n 3.] HERMANN HERBSTRITT. l.. s]

Witnesses:

EDWARD E. OsBoRN, F. H. Gnovnn. 

